The invention and subsequent dominance of the computer as the approach of choice for accumulating and manipulating data has ushered in the revolutionary age of information. This technological advance has transformed the traditional workplace and, with it, the way in which people perform their daily work. At the same time, this revolution has brought about a number of office related injuries which differ significantly from those seen in past years.
In the past, the office employee performed a great variety of physical and mental activities allowing him/her the opportunity to change positions and postures and leave a desk many times during the course of the workday. The wide range of tasks required by a worker greatly reduced or precluded the adverse effects of prolonged sitting.
Today, with office environments dominated by the computer, the adverse effects of constrained sitting postures on the worker operating a visual display terminal (V.D.T.) have become increasingly clear. Today's V.D.T. operator may spend eight hours in one posture doing two tasks using only four muscles. The operator's movements are restricted, attention is concentrated on the screen, and the hands are linked to the keyboard. The highly repetitive nature of the tasks, coupled with the prolonged postures required of the V.D.T. operator, can lead to progressive musculoskeletal damage involving the spine and extremities. Reports of physical discomfort localized in the neck-shoulder-arm area are common. This is not surprising when one considers the energy involved in maintaining an upright work posture all day. The muscles at the neck and shoulders sustain a constant holding contraction which can compress blood vessels and nerves passing through the neck on their way to the arm. Restricted circulation and nerve irritability can also lead to pain in the neck and/or upper extremities.
One observing V.D.T. operators in the workplace is struck by the sitting posture the operators often assume. Most lean back and stretch out their legs. An extensive study by Grandjean et al. looked at preferred settings of adjustable V.D.T. workstations ("V.D.T. Workstation Design: Preferred Settings and their Effects", Human Factors 25, 161-175 (1983)). The results of this field study showed that the majority of the subjects preferred trunk inclinations of between 100 degrees and 110 degrees, and the subjects preferred to rest their forearms or wrists when proper arm support was available. The relaxed, reclining posture of the V.D.T. operator commonly observed does not correspond to the recommended upright trunk posture on which today's ergonomic chairs and workstations are based.
The multiple physical problems attributable to prolonged static loading (sitting postures) and repetitive motion are well documented and supported by the medical community. They are commonly referred to as: Cumulative Trauma Disorder (C.T.D.), Overuse Syndrome, and Repetitive Motion Injury. These acute and chronic impairments include:
1. Inflammation of tendon sheaths (tendinitis or peritendinitis; e.g., carpal tunnel syndrome);
2. Inflammation of the attachment points of tendons (lateral epicondylitis, e.g., tennis elbow);
3. Inflammation of the joints (arthritis);
4. Chronic degeneration of the joints (chronic arthrosis);
5. Painful induration of muscles;
6. Intervertebral disc troubles.
The enormity of the problem can be appreciated by addressing just one of the above listed disorders. It is estimated that 80 to 90 percent of the general population will experience back problems and resulting pain sometime in their lifetime. Next to the common cold and flu, a back injury is the reason most often cited for work absenteeism. Low back pain results in 27 million lost work days annually, and in excess of 25 billion dollars is spent annually in treating back injuries.
Cumulatively, the statistics for all C.T.D. claims are equally staggering. The National Institute of Occupational Safety and Health (N.I.O.S.H.) estimates that over 5 million people suffered cumulative trauma disorders in 1986, accounting for over 30% of the total worker compensation claims. In 1984, the American Academy of Orthopedic Surgeons reported C.T.D.-related medical costs and lost earnings totalled over $27 million.